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authorTian Tao <tiantao6@hisilicon.com>2021-02-25 17:18:17 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-26 09:41:01 -0800
commitfc6697a89f56d9773b2fbff718d4cf2a6d63379d (patch)
tree9494580631437f2aecfbd2ab1116b7404f5d4a46
parentc0c641d77b9ab0da798ca86d34d2327d6f427f4c (diff)
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mm/zswap: add the flag can_sleep_mapped
Patch series "Fix the compatibility of zsmalloc and zswap". Patch #1 adds a flag to zpool, then zswap used to determine if zpool drivers such as zbud/z3fold/zsmalloc will enter an atomic context after mapping. The difference between zbud/z3fold and zsmalloc is that zsmalloc requires an atomic context that since its map function holds a preempt-disabled, but zbud/z3fold don't require an atomic context. So patch #2 sets flag sleep_mapped to true indicating that zbud/z3fold can sleep after mapping. zsmalloc didn't support sleep after mapping, so don't set that flag to true. This patch (of 2): Add a flag to zpool, named is "can_sleep_mapped", and have it set true for zbud/z3fold, not set this flag for zsmalloc, so its default value is false. Then zswap could go the current path if the flag is true; and if it's false, copy data from src to a temporary buffer, then unmap the handle, take the mutex, process the buffer instead of src to avoid sleeping function called from atomic context. [natechancellor@gmail.com: add return value in zswap_frontswap_load] Link: https://lkml.kernel.org/r/20210121214804.926843-1-natechancellor@gmail.com [tiantao6@hisilicon.com: fix potential memory leak] Link: https://lkml.kernel.org/r/1611538365-51811-1-git-send-email-tiantao6@hisilicon.com [colin.king@canonical.com: fix potential uninitialized pointer read on tmp] Link: https://lkml.kernel.org/r/20210128141728.639030-1-colin.king@canonical.com [tiantao6@hisilicon.com: fix variable 'entry' is uninitialized when used] Link: https://lkml.kernel.org/r/1611223030-58346-1-git-send-email-tiantao6@hisilicon.comLink: https://lkml.kernel.org/r/1611035683-12732-1-git-send-email-tiantao6@hisilicon.com Link: https://lkml.kernel.org/r/1611035683-12732-2-git-send-email-tiantao6@hisilicon.com Signed-off-by: Tian Tao <tiantao6@hisilicon.com> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Colin Ian King <colin.king@canonical.com> Reviewed-by: Vitaly Wool <vitaly.wool@konsulko.com> Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Reported-by: Mike Galbraith <efault@gmx.de> Cc: Barry Song <song.bao.hua@hisilicon.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Seth Jennings <sjenning@redhat.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/zpool.h3
-rw-r--r--mm/zpool.c13
-rw-r--r--mm/zswap.c51
3 files changed, 62 insertions, 5 deletions
diff --git a/include/linux/zpool.h b/include/linux/zpool.h
index 51bf43076165..e8997010612a 100644
--- a/include/linux/zpool.h
+++ b/include/linux/zpool.h
@@ -73,6 +73,7 @@ u64 zpool_get_total_size(struct zpool *pool);
* @malloc: allocate mem from a pool.
* @free: free mem from a pool.
* @shrink: shrink the pool.
+ * @sleep_mapped: whether zpool driver can sleep during map.
* @map: map a handle.
* @unmap: unmap a handle.
* @total_size: get total size of a pool.
@@ -100,6 +101,7 @@ struct zpool_driver {
int (*shrink)(void *pool, unsigned int pages,
unsigned int *reclaimed);
+ bool sleep_mapped;
void *(*map)(void *pool, unsigned long handle,
enum zpool_mapmode mm);
void (*unmap)(void *pool, unsigned long handle);
@@ -112,5 +114,6 @@ void zpool_register_driver(struct zpool_driver *driver);
int zpool_unregister_driver(struct zpool_driver *driver);
bool zpool_evictable(struct zpool *pool);
+bool zpool_can_sleep_mapped(struct zpool *pool);
#endif
diff --git a/mm/zpool.c b/mm/zpool.c
index 3744a2d1a624..5ed71207ced7 100644
--- a/mm/zpool.c
+++ b/mm/zpool.c
@@ -23,6 +23,7 @@ struct zpool {
void *pool;
const struct zpool_ops *ops;
bool evictable;
+ bool can_sleep_mapped;
struct list_head list;
};
@@ -183,6 +184,7 @@ struct zpool *zpool_create_pool(const char *type, const char *name, gfp_t gfp,
zpool->pool = driver->create(name, gfp, ops, zpool);
zpool->ops = ops;
zpool->evictable = driver->shrink && ops && ops->evict;
+ zpool->can_sleep_mapped = driver->sleep_mapped;
if (!zpool->pool) {
pr_err("couldn't create %s pool\n", type);
@@ -393,6 +395,17 @@ bool zpool_evictable(struct zpool *zpool)
return zpool->evictable;
}
+/**
+ * zpool_can_sleep_mapped - Test if zpool can sleep when do mapped.
+ * @zpool: The zpool to test
+ *
+ * Returns: true if zpool can sleep; false otherwise.
+ */
+bool zpool_can_sleep_mapped(struct zpool *zpool)
+{
+ return zpool->can_sleep_mapped;
+}
+
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
MODULE_DESCRIPTION("Common API for compressed memory storage");
diff --git a/mm/zswap.c b/mm/zswap.c
index 1e41c2857068..578d9f256920 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -935,13 +935,19 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
struct scatterlist input, output;
struct crypto_acomp_ctx *acomp_ctx;
- u8 *src;
+ u8 *src, *tmp = NULL;
unsigned int dlen;
int ret;
struct writeback_control wbc = {
.sync_mode = WB_SYNC_NONE,
};
+ if (!zpool_can_sleep_mapped(pool)) {
+ tmp = kmalloc(PAGE_SIZE, GFP_ATOMIC);
+ if (!tmp)
+ return -ENOMEM;
+ }
+
/* extract swpentry from data */
zhdr = zpool_map_handle(pool, handle, ZPOOL_MM_RO);
swpentry = zhdr->swpentry; /* here */
@@ -955,6 +961,7 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
/* entry was invalidated */
spin_unlock(&tree->lock);
zpool_unmap_handle(pool, handle);
+ kfree(tmp);
return 0;
}
spin_unlock(&tree->lock);
@@ -979,6 +986,14 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
dlen = PAGE_SIZE;
src = (u8 *)zhdr + sizeof(struct zswap_header);
+ if (!zpool_can_sleep_mapped(pool)) {
+
+ memcpy(tmp, src, entry->length);
+ src = tmp;
+
+ zpool_unmap_handle(pool, handle);
+ }
+
mutex_lock(acomp_ctx->mutex);
sg_init_one(&input, src, entry->length);
sg_init_table(&output, 1);
@@ -1033,7 +1048,11 @@ fail:
spin_unlock(&tree->lock);
end:
- zpool_unmap_handle(pool, handle);
+ if (zpool_can_sleep_mapped(pool))
+ zpool_unmap_handle(pool, handle);
+ else
+ kfree(tmp);
+
return ret;
}
@@ -1235,7 +1254,7 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
struct zswap_entry *entry;
struct scatterlist input, output;
struct crypto_acomp_ctx *acomp_ctx;
- u8 *src, *dst;
+ u8 *src, *dst, *tmp;
unsigned int dlen;
int ret;
@@ -1253,15 +1272,33 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
dst = kmap_atomic(page);
zswap_fill_page(dst, entry->value);
kunmap_atomic(dst);
+ ret = 0;
goto freeentry;
}
+ if (!zpool_can_sleep_mapped(entry->pool->zpool)) {
+
+ tmp = kmalloc(entry->length, GFP_ATOMIC);
+ if (!tmp) {
+ ret = -ENOMEM;
+ goto freeentry;
+ }
+ }
+
/* decompress */
dlen = PAGE_SIZE;
src = zpool_map_handle(entry->pool->zpool, entry->handle, ZPOOL_MM_RO);
if (zpool_evictable(entry->pool->zpool))
src += sizeof(struct zswap_header);
+ if (!zpool_can_sleep_mapped(entry->pool->zpool)) {
+
+ memcpy(tmp, src, entry->length);
+ src = tmp;
+
+ zpool_unmap_handle(entry->pool->zpool, entry->handle);
+ }
+
acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
mutex_lock(acomp_ctx->mutex);
sg_init_one(&input, src, entry->length);
@@ -1271,7 +1308,11 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
ret = crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait);
mutex_unlock(acomp_ctx->mutex);
- zpool_unmap_handle(entry->pool->zpool, entry->handle);
+ if (zpool_can_sleep_mapped(entry->pool->zpool))
+ zpool_unmap_handle(entry->pool->zpool, entry->handle);
+ else
+ kfree(tmp);
+
BUG_ON(ret);
freeentry:
@@ -1279,7 +1320,7 @@ freeentry:
zswap_entry_put(tree, entry);
spin_unlock(&tree->lock);
- return 0;
+ return ret;
}
/* frees an entry in zswap */